The present invention describes a footwear device that is intended to be worn inside an article of footwear or be an integral part of an article of footwear. Such devices that are worn inside an article of footwear are commonly referred to as insoles, orthotics, sockliners, footbeds, inserts, or arch supports. For the purposes of this invention, this type of footwear device will be referred to as a supportive performance insole, or insole for brevity.
The said device described by this invention is constructed of a foam layer, a textile layer, and a composite material layer that includes a fiber reinforcement phase and a polymer matrix phase that binds the reinforcement phase together.
In addition, the said footwear device comprises a light-cured polymer matrix that binds the reinforcement phase. Unlike conventional polymer-matrix fiber-reinforced composite materials that utilize a polymer that is thermally cured, a light-curable matrix will cure when exposed to light with a specific wavelength range and sufficient energy, or dosage. Generally the light used to cure light-curable polymer materials is in or near the UV spectrum and the fibers used as the reinforcement phase are glass fibers because of their transparency to UV light.
One advantage of light-cured composite materials is that the time required to polymerize the matrix phase from a liquid monomer to a solid polymer can be much less (seconds to minutes) than the time it takes to thermally cure polymers used in conventional composites (generally hours).
Another advantage of light-curable composite materials is that heat does not need to be applied to the material during the curing cycle, which opens the option for alternative, lower-cost molding materials to shape the composite that could not survive or perform their intended function at the elevated temperatures (generally >250 F) and pressures that are required for traditionally thermally-cured composites.
Light-cured composite materials also enable flat foam materials to maintain the desired shape of a performance insole, which generally includes a shaped arch and heel cup. By maintaining the shape of the insole with a light-cured composite supportive layer, it avoids the added cost and complexity of compression or injection molding the foam to create the desired shape of the insole.
Prior art such as U.S. Pat. Nos. 5,632,057 and 6,939,502 by Lyden, describe methods to create light-cured footwear articles; however, this prior art relies on a rigid mold or surface to define the shape of the light-cured article, thus limiting the shape and performance of a composite support plate.
Additional relevant prior art include U.S. Pat. Nos. 6,490,730, 6,681,403, and 7,003,803, also by Lyden. In this prior art, Lyden describes light-cured articles of protective equipment and methods to fabricate the articles directly on the relevant area of the body. However, the described methods in this prior art can be cumbersome and dangerous if the UV-resin gets too hot during curing.
What is needed is an insole device that can take advantage of the performance benefits of fiber-reinforced composite materials without added manufacturing complexity. Insoles constructed of fiber-reinforced composite materials can be stiffer and lighter than other common materials used to construct supportive insoles, such as injection molded plastics. In addition, simpler and safer methods and systems are necessary to efficiently and quickly manufacture high-quality, custom shaped performance insoles directly on a person's foot; particularly methods that offer greater conformability to the foot without having the person in a full weight-bearing position.